As a multilayer structure suitable as an automotive fuel tank, there has been proposed a multilayer structure formed from a polyethylene resin layer/an adhesive layer/an ethylene•vinyl acetate copolymer saponification product layer (hereinafter also abbreviated as the “EVOH”) or formed from a polyethylene resin/a mixture layer of an adhesive and an ethylene•vinyl acetate copolymer saponification product (for example, Patent Document 1).
As the adhesive layer of this multilayer structure, a composition containing an ethylene polymer partly or wholly graft-modified with an acid anhydride is used. However, if a modified ethylene polymer with low density is used, the resultant adhesive layer, when immersed in a fuel oil, may be swollen, and may have reduced adhesive strength at high temperature. On the other hand, if a modified ethylene polymer with high density is used, the resultant multilayer structure may have reduced low-temperature drop impact strength.
The demand for higher performance of automotive fuel tanks has been increasing. For example, as a result of diesel automobiles adopting a common rail system, in addition to the performance required so far, the automotive fuel tanks are required to have long-term durability when in contact with high-temperature fuels. Specifically, for example, the multi-layer structure is required to be free from problems such as delamination between respective layers and delamination at the pinch-off part, even when in contact with high-temperature fuel.